Thread cutter for sewing machines



Oct. 18,1932- A ERICSSON THREAD CUTTER FOR SEWING MACHINES Original Filed May 18', 192'? 2 Sheets-Sheet '1 Oct. 18, 1932'. g cssaN 1,883,654

THREAD CUTTER TOR SEWING MACHINES Qriginal' Filed May 18. 1927 2 Sheets-Sheet 2 Patented Get. 18, 1932 air TATES PATENT orrlcr.

ARVIID naicsson, or cnrceso, rnrlrnors'nssrenoa To onion s'PEcIAI. MACHINE can. rnnv, or cnrcnco, ILLINOIS; A CORPORATION THREAD CUTTER FOR SEWING MACHINES QriginaI application filed May 18; 1927, Serial No. 192.249. Divided and this application filed. July 29. 1929.

' Serial No. 381,878.

The invention relates to new and useful improvements in thread cutters for sewing machines and more particularly to'a thread cutter which may be operated for severing the threads at the end of the operation of the stitching of the article.

An ob'ect of the invention is to rovide a thread cutting mechanism which includes. a stationary cutting blade with means for clamping the thread and subsequently shift ing the clamped thread into contact with the cutting blade for severing the thread at one side of the clamping member.

A further object of the invention is to provide a thread cutting mechanism of the above type wherein the thread clamping means includes a yieldingly mounted member and a positively moved member which moves said yielding member after the thread is clamped so as to bring the thread into contact with the cutting blade.

These and other objects will in .part bev obvious and will in part behereinafter more fully disclosed. I

In the drawings which show by way of illustration one embodiment of the invention:--

Fig. l is a view partly in section and partly in end elevation showing a portion of a button sewing machine having the unprovements applied thereto for cutting the needle and looper threads after the button -has been stitched to the fabric, the parts being positioned so as to permit stitching.

F lg. 2 is a similar view but showing the needle and looper thread as clamped prepara; tory to the shifting of the same into contact with the stationary cutting blade.

Fig. 3 is a detail showing the position of e cutting blade and the clamping device ter the thread is severed. V Fig. 4 is a plan view with parts broken th a f away and parts in section showing thecutting blade in plan and the associated thread clamping means. A r Fig. 5 is a perspective vlewshowlng the cutting blade removed and the yielding clamping member of the thread clamping DIGZLIIS.

Fig. 6 is a detail showing more or less dia-' grammatically. and in plan the position of the threads at the time when they are clamped for the purpose of presenting the same to the'stationary cutting blade.

The invention is directed broadly to a thread cutting device associated with a stitching mechanism so that after the stitching op-,,

of the stitching point and when operated moves across the needle path into engagement with one strandof the needle thread loop on. the looper and the looper thread moving said needle thread and looper thread strands into engagement with the clamping member for clamping the same, after which the clamping j member yields so that the. clamped threads" are carried into contact with the cut-ting blade and severed.

Referring more indetailto the drawings,

the invention is shown as applied to a Ina-- chine for stitching buttons to a fabric. ,-.The

machine to which the invention is applied is shown anddescribed in detail in my .copending application Serial No.'192,249 filed May 18, 1927, of whichfthis application is a division.

The jmachine includes a cylindrical work supporting melnberl carrying a fabric sup-, porting plate 2. Directly above the fabric supporting plate are button clampingjaws '3':

which support'the button; Between these.- clamping jaws and the plate 2is a plate .45. The fabric is placed on this plate .4 and the button in the clamping jaws and the latter is secured to the fabric by a stitchingmecha nism which includes a needle 5 anda'coop erating looper 6. There is anopening'Z through the plate 2througl1which the needle passes. Cooperating with the looper and needle is a loop retainer 8. The looper is mounted on a shaft 9 and is oscillated thereby. The retainer is mounted on a pivot 10 carried by the work supporting arm and is oscillated by a cam 11. Both the looper and retainer have a lateral movement which as sists in the stitch formation. The stitch forming mechanism as illustrated forms no part of the present invention, but is shown and described in my co-pending application above referred to.

The present invention has to do with the thread cutter and includes a stationary thread cutting blade 12. The plate 2 is mounted on abracket 13 and the stationary cutting blade 12 is disposed between the bracket 13 and the plate 2. Said cutting blade 12 is beveled at its inner end forming a cutting edge is at the lower sidethereof. This cutting edge 14: is located at one side of the opening 7 through which the needle reciprocates. Located directly beneath the cutting blade 12 is a thread clamping member 15. This thread clamping member 15 is mounted in a guideway formed in the bracket 13 (see Fig. 5). The upper face of the clamping member 15 is substantially flush with the upper face of the bracket 13. The cutting blade 12 makes contact with this clamping member 15. A spring 16 bearing'against the outer end of the clamping member normally presses said clamping memher in a direction toward the opening 7 for the needle.

Shoulders 17 are provided on the clamping member which engage stops formed on the bracket 13 and this limits the inward move ment of the clamping member 15. The extreme inner end of the clamping member 15 is inclined as indicated at 18. When the clamping member is at its extreme inner position it projects beyond the cutting edge 14 of the cutting blade and extends to a certain extent across the opening 7 lit is, however, so positioned that when projected inwardly to its fullest extent it does not in any way interfere with the reciprocation of the needle and the formation of the stitches. Cooperating with this yielding clamping member 15 is a positively moved clamping finger 18a. This clamping finger 18a is carried by an arm 19 fixed to a sleeve 20 surrounding the shaft 9 which is the looper shaft of the machine. The sleeve 20 may be oscillated by any suitable device.

In the machine of my co-pending application above referred to this sleeve is adapted to be oscillated automatically by a control cam which causes the finger to move across in the needle path and into engagement with one strand of the needle thread loop on the looper and also the looper thread leading from the eye of the looper to the previous stitch. When the finger 18a comes into contact with the threads as stated it will move 9 the threads into contact w1th the inclined end 18 of the yielding clamping member. A con tinued movement of this clamping finger 18a Will cause said yielding clamping member to move outwardly and thus the clamped threads are brought into engagement with the cutting edge 1% of the cutting member 12 and are severed.

In Fig. 6 of the drawings, the looper is indicated at 6, the looper thread at 1 and it will be noted that this thread 1 extends from the eye of the looper to the clamping means where it is clamped and thence from the clamping means to the previous stitch. When this looper thread is severed, it will be severed between the looper and the fabric and the end of the thread leading to the material will be free while the end of-tne thread leading to the eye of the looper will be clamped. Thus it is that the looper thread is held and clamped for the beginning of the next stitching operation.

The strand t of the needle thread loop is clamped and cut. The end of the strand running to the previous stitch is free. The end of the strand, however, running about the looper and up through the fabric to the needle eye is clamped; The machine as set forth in my co-pending application is provided with means for drawing off thread just before the machine stops and one of the purposes of clamping this end of the needle thread is to draw a sulficient length of needle thread through the eye of the needle to aid in the beginning of the next stitching operation.

Tt will be seen, therefore, that the looper thread is clamped preparatory to the next stitching operation. The needle thread is held by the clamp, but as it runs through the fabric to the clamp when the fabric is removed, it will pull on the needle thread and this will pull the slack thread through the eye of the needle and then the thread will be pulled out of the clamp. After the cutting operation and the removal of the fabric there is a sufficient length of thread pulled through the eye of the needle so that the next stitching operation can be readily started so far as the needle thread is concerned and the clamping of the looper thread although asjacent the eye of the looper will hold the looper thread so that a pro aer stitch formation can be accomplished. The finger is preferably held clamping the looper thread until after several stitches have been formed so as to insure a proper holding of the looper thread for the formation of the stitches.

While the thread cutter is shown as used in connection with a button sewing machine it will be obvious that it is capable of use in connection with other types of sewing machines. It will. be obvious that minor changes in the details of construction and the arrangement of the parts may be made without deber associated with the stationary cutting member and disposed at the same side of the needle path, a positively operated clamping member normally disposed at the other sideof the needle path and adapted to move across said needle path to engage the stitching'threads, clamp the same against the yielding clamping member and move said clamped threads and yielding clamping member so as to cause said stitching threads to engage and be severed by the stationary cutting member.

2. A thread cutter for sewing machines comprising a stationary cutting member disposed in a fixed position at one side of the needle path, a clamping member located at the same side of the needle path and beneath said stationary cutting member and normally projecting beyond the cutting edge of the cutting member, a spring for holding said clamping member projected, a thread engaging arm, means for supporting said arm and for moving the same across the needle path and into engagement with the threads to be cut for clamping said threads against the end of the clamping member and for moving the clamping member to bring the threads into engagementwith the cutting edge of the cutting member. i

3. A thread cutter for sewing machines comprising a stationary cutting member disposed in a fixed position at one side of the needle path, a clamping member associated with said cutting member and located on the same side of the needle path and below the cutting member and normally projecting beyond the cutting edge thereof, a spring bearing on said clamping member for holding the same projected, a thread arm, means for supporting and moving said thread arm across the needle path for engaging the threads and clamping the same against the end of said clamping member and for moving said clamping member to cause the threads to engage the cutting edge of the cutting member, said thread engaging arm being normally spaced away from the clamping member so that the stitching needle may reciprocate between said thread engaging arm and said clamping member.

4. The combination with a thread carrying needle, a thread carrying looper, a stationary cutting blade located at one side of the path of said needle, means for engaging the looper thread between the eye of the looper and the previous stitch and one strand of the needle thread loop while about the looper for moving said strand and the looper thread into engagement with the cutting edge of the cutting member. 7

5. The combination with a thread carrying needle, a thread carrying looper, a stationary cutting blade located at one side of the path of said needle, a yielding clamping member associated with said cutting member and disposed upon the same side of the needle path as the cutting member, a thread arm normally located at the opposite side of the needle path from the stationary cutting blade and adapted to move across the needle path and engage the stitching threads for clamping said stitching threads against said clamping member and for moving the clamped threads into engagement with the cutting edge of the cutting member.

6. The combination with a thread carrying needle, a thread carrying looper, a stationary cutting blade located at one side of V the path of said needle, and thread clamping means for engaging the looper thread between the eye of the looper and the previous stitch and the strand of the needle thread loop on the looper extending from the looper to the previous stitch for carrying said threads into engagement with the cutting member for severing the same.

7. The combination with a thread carrying needle, a thread carrying looper, a stationary cutting blade located at one side of the path of said needle, a yielding thread clamping member located on the same side of the needle path as the thread cutting member and, disposedso as to project in front of the cutting edge of said cutting member,

a thread arm normally disposed on the opposite side of the needle path and movable across said needle path into engagement with the looper thread between the eye of the looper and the previous stitch and the strand of the needle thread loop while on the looper between the looper and the previous stitch for clamping the threads against said clamping member and moving said threads into engagement with the cutting edge of the cutting member.

' In testimony whereof, I afiix my signature.

ARVID ERICSSON. 

